The present invention relates to an apparatus for controlling a file system and a storage system for storing data of the file system.
File services using a NAS (Network Attached Storage) system that functions both as a file server for controlling a file system and as a storage system for storing data of the file system have been recently in demand. Accordingly, as the capacity of data stored in the NAS system increases, the number of disk devices of the storage system in the NAS system increases.
When the number of the disk devices increases, the power consumption of the storage system also increases. In particular, in a large capacity disk array system that is equipped with a plurality of disk devices and has RAID (Redundant Array of Inexpensive Disks) composed of a plurality of disk devices, the storage system consumes too much power.
U.S. Pat. No. 6,826,005 discloses a method of reducing the power consumption of the disk array system by stopping (spinning down) the disk device that is not accessed by an upper-level device for a predetermined time interval.